Ataxin 7 (ATXN7) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
of the SCA7 gene, which contains 892 amino acids with an expandable poly(Q) region close to the
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
. The expandable poly(Q) motif region in the protein contributes crucially to
spinocerebellar ataxia
Spinocerebellar ataxia (SCA) is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a neurological condition in its own right. An estimated 150,000 people in the United States have a diagnosis of s ...
(SCA) pathogenesis by the induction of intranuclear
inclusion bodies
Inclusion bodies are aggregates of specific types of protein found in neurons, a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells ...
. ATXN7 is associated with both
olivopontocerebellar atrophy
Olivopontocerebellar atrophy (OPCA) is the degeneration of neurons in specific areas of the brain – the cerebellum, pons, and inferior olivary nucleus. OPCA is present in several neurodegenerative syndromes, including inherited and non-inherited ...
type 3 (OPCA3) and
spinocerebellar ataxia
Spinocerebellar ataxia (SCA) is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a neurological condition in its own right. An estimated 150,000 people in the United States have a diagnosis of s ...
type 7 (SCA7).
CAG repeat
Trinucleotide repeat disorders, also known as microsatellite expansion diseases, are a set of over 50 genetic disorders caused by trinucleotide repeat expansion, a kind of mutation in which repeats of three nucleotides ( trinucleotide repeats) inc ...
leads to pathological protein misfolding. In ataxin-7 gene has shown to cause cerebellar and brainstem degeneration as well as retinal
conerod dystrophy. Polyglutamine (polyQ) expansion at the N-terminus of ataxin-7 causes protein aggregation, leading to the symptoms of ataxia with visual loss.
Research suggest that silencing of ataxin-7 in the retina by
RNAi
RNA interference (RNAi) is a biological process in which RNA molecules are involved in sequence-specific suppression of gene expression by double-stranded RNA, through translational or transcriptional repression. Historically, RNAi was known by o ...
can be a possible therapeutic strategy for patients with SCA7 retinal degeneration.
References
Further reading
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External links
GeneReviews/NCBI/NIH/UW entry on Spinocerebellar Ataxia Type 7*
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Proteins
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